1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 package com.android.documentsui.dirlist; 17 18 import static android.support.v4.util.Preconditions.checkState; 19 import static com.android.documentsui.base.SharedMinimal.VERBOSE; 20 21 import android.content.Context; 22 import android.os.Build; 23 import android.support.annotation.Nullable; 24 import android.support.v7.widget.RecyclerView; 25 import android.support.v7.widget.RecyclerView.OnItemTouchListener; 26 import android.util.Log; 27 import android.view.MotionEvent; 28 import android.view.ScaleGestureDetector; 29 30 import com.android.documentsui.base.Features; 31 32 import java.util.function.Consumer; 33 34 /** 35 * Class providing support for gluing gesture scaling of the ui into RecyclerView + DocsUI. 36 */ 37 final class ScaleHelper { 38 39 private static final String TAG = "ScaleHelper"; 40 41 private final Context mContext; 42 private final Features mFeatures; 43 private final Consumer<Float> mScaleCallback; 44 45 private @Nullable ScaleGestureDetector mScaleDetector; 46 ScaleHelper(Context context, Features features, Consumer<Float> scaleCallback)47 public ScaleHelper(Context context, Features features, Consumer<Float> scaleCallback) { 48 mContext = context; 49 mFeatures = features; 50 mScaleCallback = scaleCallback; 51 } 52 onInterceptTouchEvent(RecyclerView rv, MotionEvent e)53 private boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) { 54 // Checking feature is deferred to runtime so the feature can be enabled 55 // after this class has been setup. 56 if (mFeatures.isGestureScaleEnabled() && mScaleDetector != null) { 57 mScaleDetector.onTouchEvent(e); 58 } 59 60 return false; 61 } 62 attach(RecyclerView view)63 void attach(RecyclerView view) { 64 checkState(Build.IS_DEBUGGABLE); 65 checkState(mScaleDetector == null); 66 67 mScaleDetector = new ScaleGestureDetector( 68 mContext, 69 new ScaleGestureDetector.SimpleOnScaleGestureListener() { 70 @Override 71 public boolean onScale(ScaleGestureDetector detector) { 72 if (VERBOSE) Log.v(TAG, 73 "Received scale event: " + detector.getScaleFactor()); 74 mScaleCallback.accept(detector.getScaleFactor()); 75 return true; 76 } 77 }); 78 79 view.addOnItemTouchListener( 80 new OnItemTouchListener() { 81 @Override 82 public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) { 83 return ScaleHelper.this.onInterceptTouchEvent(rv, e); 84 } 85 86 @Override 87 public void onTouchEvent(RecyclerView rv, MotionEvent e) {} 88 89 @Override 90 public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {} 91 }); 92 } 93 } 94